Observation of τ⁻→π⁻ν^τe⁺e⁻ and search for τ⁻→π⁻ντμ⁺μ⁻

Author(s)

Y. Jin
H. Aihara
D. Epifanov
I. Adachi
S. AI. Said
D. M. Asner
V. Aulchenko
T. Aulchenko
T. Aushev
R. Ayad
V. Babu
I. Badhrees
S. Bahinipati
V. Bansal
P. Behera
M. Berger
V. Bhardwaj
T. Bilka
J. Biswal
Milind Purohit, University of South CarolinaFollow
Et. Al.

Document Type

Article

Abstract

We present the first measurements of branching fractions of rare tau-lepton decays, τ−→π−ντℓ+ℓ− (ℓ=e or μ), using a data sample corresponding to 562 fb⁻¹ collected at a center-of-mass energy of 10.58 GeV with the Belle detector at the KEKB asymmetric-energy e⁺e⁻collider. The τ−→π⁻ν_τe⁺e⁻ decay is observed for the first time with 7.0σ significance. The partial branching fraction determined by the structure-dependent mechanisms mediated by either a vector or an axial-vector current for the mass region M_πee > 1.05 GeV=c² is measured to be B(τ⁻ → π⁻ν_τe⁺e⁻)[M_π−e+e− > 1.05 GeV=c² ]= (5.90 ± 0.53 ± 0.85 ± 0.11) × 10⁻⁶, where the first uncertainty is statistical, the second is systematic, and the third is due to model dependence. In the full phase space, due to the different detection efficiencies for the structure-dependent mechanisms mediated by axial-vector and vector currents, the branching fraction varies from B_A(τ⁻ → π⁻ν_τe⁺e⁻)[(1.46± 0.13± 0.21) × 10⁻⁵ to B_V(_τ− → π⁻ν_τe⁺e⁻)[(3.01± 0.27 ±0.43) × 10⁻⁵, respectively. An upper limit is set on the branching fraction of the τ⁻ → π⁻ντμ+μ− decay, B(τ⁻ → π⁻ντμ⁺μ⁻) < 1.14 × 10⁻⁵, at the 90% confidence level.

Digital Object Identifier (DOI)

https://doi.org/10.1103/PhysRevD.100.071101

Publication Info

Published in Physical Review D, Volume 100, Issue 7, 2019.

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Rights

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

APA Citation

Jin, Y., Aihara, H., Epifanov, D., Adachi, I., Al Said, S., Asner, D. M., Aulchenko, V., Aushev, T., Ayad, R., Babu, V., Badhrees, I., Bahinipati, S., Bansal, V., Behera, P., Berger, M., Bhardwaj, V., Bilka, T., Biswal, J., Bobrov, A., … Zhukova, V. (2019). Observation of . Physical Review D, 100(7). https://doi.org/10.1103/physrevd.100.071101